In the field of telecommunications, various types of communication networks are known. These include, on the one hand, communication networks which are based on the common channel signaling system No. 7 (CCS7) and are occasionally called “traditional” networks. They include public switched telephone networks (PSTN) and public land mobile networks (PLMN). In the past, voice-based communication was primarily conducted via these “traditional” networks. In these networks, the subscribers are addressed via telephone directory numbers which are also called E.164 numbers. On the other hand, networks are also known which are based on the Internet Protocol (IP) . Voice transmission over such IP networks, which is called “Voice over IP” (VoiP) is becoming more and more widespread. In these networks, the subscribers are addressed via addresses which conform to the Internet Protocol; this includes Internet addresses and E-mail addresses.
A subscriber to a “traditional” network cannot easily set up a voice link to a subscriber of an Internet Protocol-based network (IP network) because addresses conforming to the IP (IP addresses) cannot be processed in the “traditional” networks.